Organic electronic devices comprising a layer of a pyridine compound and a 8-hydroxypquinolinolato earth alkaline metal, or alkali metal complex

ABSTRACT

The present invention provides an organic electronic device including a first electrode, a second electrode, and an organic layer interposed between the first electrode and the second electrode, wherein the organic layer comprises an organic metal complex of formula 
     
       
         
         
             
             
         
       
     
     and a compound of formula 
     
       
         
         
             
             
         
       
     
     Organic light emitting devices (OLEDs) having superior life time, power efficiency, quantum efficiency and/or a low operating voltage are obtained, when the organic layer comprising the compounds of formula I and II constitutes the electron transport layer of an OLED.

CROSS REFERENCES

This application claims the benefit of U.S. Provisional Application No.61/356,058, filed Jun. 18, 2010.

The present invention provides an organic electronic device including afirst electrode, a second electrode, and an organic layer interposedbetween the first electrode and the second electrode, wherein theorganic layer comprises an organic metal complex of formula I and acompound of formula II.

WO10072300 relates to organic electroluminescent devices which comprisetriazine derivatives optionally in combination with an organic alkalimetal compound as the electron trans-port material. As an example of anorganic alkali metal compound lithium quinolate is mentioned.

M. Thelakkat et al., Chem. Mater. 12 (2000) 3012-3019 describes thesynthesis of lithiumquinolate complexes, 8-hydroxyquinolinolatolithium(Liq) and 2-methyl-8-hydroxyquinolinolatolithium (LiMeq) and their useas emitter and electron injection/transport materials in conventionaltwo-layer organic light-emitting diodes in combination withN,N″-bis(p-methoxyphenyl)-N,N′-diphenylbenzidine (DMeOTPD) as holetransport material (HTL). The lithium complexes were also examined asinterface materials in combination with 8-hydroxyquinolinolato-Al(III)(Alq₃) as emitter material. The lithium complexes increase theefficiency of an optimized indium-tin oxide (ITO)/DMeOTPD/Alq₃/Aldeviceconsiderably when used as a thin interface layer between Alq₃ andaluminum. The improvement of device characteristics with lithiumquinolates is similar to that obtained with LiF salt.

Z. L. Zhang et al., Synthetic Metals 158 (2008) 810-814 describesorganic light-emitting diodes with 8-hydroxy-quinolinato lithium doped4′,7-diphenyl-1,10-phenanthroline as electron transport layer (ETL), andtetrafluoro-tetracyano-quinodimethane doped4,4′,4″-tris(3-methylphenylphenylamino)triphenylamine as hole transportlayer (HTL). Compared with the referenced device (without doping), thecurrent efficiency and power efficiency of the p-i-n device are enhancedby approximately 51% and 89%, respectively. This improvement isattributed to the improved conductivity of the transport layers and theefficient charge balance in the emission zone.

US2007252521A1 describes an electroluminescent device comprising acathode, an anode, and has therebetween a light emitting layer (LEL),the device further containing an electron transport layer (ETL) on thecathode side of the LEL and an organic electron injection layer (EIL)contiguous to the ETL on the cathode side, wherein the ETL contains amonoanthracene compound bearing aromatic groups in the 2-, 9-, and10-positions.

A material represented by formula

may be included in the electron injection layer. M² represents an alkalior alkaline earth metal. r^(a) and r^(b) represents an independentlyselected substituent, provided two substituents may combine to form afused ring group. Examples, of such substituents include a methyl group,a phenyl group, a fluoro substituent and a fused benzene ring groupformed by combining two substituents. h and i are independently 1-3, andq is an integer from 1 to 6.

An example of a material of Formula (6b) is lithium quinolate. In oneembodiment, a lithium complex of an 8-hydroxyquinolate group is includedin the electron injection layer.

A 2,2′-bipyridyl material, such as, for example,

may be included in the electron injection layer.

It was the object of the present invention to provide organic electronicdevices, especially organic light emitting devices showing goodefficiencies, good operative lifetimes and a high stability to thermalstress, and a low operating voltage.

Said object has been solved by an organic electronic device including afirst electrode, a second electrode, and an organic layer interposedbetween the first electrode and the second electrode, wherein theorganic layer comprises an organic metal complex of formula

anda compound of formula

whereinR¹ and R² are independenly of each other F, C₁-C₈alkyl, or C₆-C₁₈aryl,which may optionally be substituted by one, or more C₁-C₈alkyl groups,ortwo substituents R¹ and/or R² combine to form a fused benzene ringgroup, which may optionally be substituted by one, or more C₁-C₈alkylgroups,a and b are independently of each other 0, or an integer 1 to 3,R⁸¹, R⁸², R⁸³, R⁸⁴, R⁸¹′, R⁸²′, R⁸³′, and R⁸⁴′ are independently of eachother H, C₁-C₁₈alkyl, C₁-C₁₈alkyl which is substituted by E and/orinterrupted by D, C₆-C₂₄aryl, C₆-C₂₄aryl which is substituted by G,C₂-C₂₀heteroaryl, or C₂-C₂₀heteroaryl which is substituted by G,Q is an arylene or heteroarylene group, each of which may optionally besubstituted by G;D is —CO—; —COO—; —S—; —SO—; —SO₂—; —O—; —NR²⁵—; —SiR³OR³¹—; —POR³²—;—CR²³═CR²⁴—; or —CC—; andE is —OR²⁹; —SR²⁹; —NR²⁵R²⁶; —COR²⁸; —COOR²⁷; —CONR²⁵R²⁶; —CN; or F; Gis E, C₁-C₁₈alkyl, C₁-C₁₈alkyl which is interrupted by D,C₁-C₁₈perfluoroalkyl, C₁-C₁₈alkoxy, or C₁-C₁₈alkoxy which is substitutedby E and/or interrupted by D, whereinR²³ and R²⁴ are independently of each other H, C₆-C₁₈aryl; C₆-C₁₈arylwhich is substituted by C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; C₁-C₁₈alkyl; orC₁-C₁₈alkyl which is interrupted by —O—;R²⁵ and R²⁶ are independently of each other C₆-C₁₈aryl; C₆-C₁₈aryl whichis substituted by C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; C₁-C₁₈alkyl; orC₁-C₁₈alkyl which is interrupted by —O—; orR²⁵ and R²⁶ together form a five or six membered ring, R²⁷ and R²⁸ areindependently of each other C₆-C₁₈aryl; C₆-C₁₈aryl which is substitutedby C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; C₁-C₁₈alkyl; or C₁-C₁₈alkyl which isinterrupted by —O—,

R²⁹ is C₆-C₁₈aryl; C₆-C₁₈aryl, which is substituted by C₁-C₁₈alkyl, orC₁-C₁₈alkoxy; C₁-C₁₈alkyl; or C₁-C₁₈alkyl which is interrupted by —O—,

R³⁰ and R³¹ are independently of each other C₁-C₁₈alkyl, C₆-C₁₈aryl, orC₆-C₁₈aryl, which is substituted by C₁-C₁₈alkyl,R³² is C₁-C₁₈alkyl, C₆-C₁₈aryl, or C₆-C₁₈aryl, which is substituted byC₁-C₁₈alkyl M is an alkali metal atom, or an earth alkaline metal atom,n is 1, if M is an alkali metal atom, n is 2, if M is an earth alkalimetal atom.

OLEDs having superior life time, power efficiency, quantum efficiencyand/or a low operating voltage are obtained, when the organic layercomprising the compounds of formula I and II constitutes the electrontransport layer of an OLED.

Examples of M are Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, or Ba. Li, Na and Kare preferred, Li is most preferred. Examples of the metal complex offormula I are 8-hydroxyquinolinolato lithium (Liq) and2-methyl-8-hydroxyquinolinolato lithium (LiMeq). The most preferredmetal complex is

which can exist as the single species, or in other forms such asLi_(g)Q_(g), where g is an integer, for example Li₆Q₆. Q represents8-hydroxyquinolate ligand or a derivative of 8-hydroxyquinolate

R⁸¹, R⁸², R⁸³, and R⁸⁴ are preferably independently of each other H, orC₁-C₁₈alkyl, more preferably H. R⁸¹′, R⁸²′, R⁸³′, and R⁸⁴′ arepreferably independently of each other H, or C₁-C₁₈alkyl, morepreferably H.

Q is preferably a group of formula

wherein R⁸⁵ is H, C₁-C₁₈alkyl, C₁-C₁₈alkyl which is substituted by Eand/or interrupted by D, C₆-C₂₄aryl, C₆-C₂₄aryl which is substituted byG, C₂-C₂₀heteroaryl, or C₂-C₂₀heteroaryl which is substituted by G, andD, E and G are as defined above.

Compounds of formula II are even more preferred, wherein Q is a group offormula

R⁸⁵ is H, C₁-C₁₈alkyl, C₁-C₁₈alkyl which is substituted by E and/orinterrupted by D, C₆-C₂₄aryl, C₆-C₂₄aryl which is substituted by G,C₂-C₂₀heteroaryl, or C₂-C₂₀heteroaryl which is substituted by G, and D,E and G are as defined above.

Groups of formula

are most preferred.

Compounds of formula

are preferred, wherein Q is a group of formula

R⁸⁵ is H, C₁-C₁₈alkyl, C₁-C₁₈alkyl which is substituted by E and/orinterrupted by D, C₆-C₂₄aryl, C₆-C₂₄aryl which is substituted by G,C₂-C₂₀heteroaryl, or C₂-C₂₀heteroaryl which is substituted by G, and D,E and G are as defined above. In said embodiment R⁸¹, R⁸², R⁸³, and R⁸⁴are preferably independently of each other H, or C₁-C₁₈alkyl.

Compounds of formula

such as, for example,

are even more preferred, wherein

Q is

R⁸⁵ is H, or C₁-C₁₈alkyl andR⁸⁵′ is H, C₁-C₁₈alkyl, or

Particularly preferred compounds of formula II are compounds A-1 toA-27. Reference is made to claim 4. Compound A-1 is at present mostpreferred.

In a particularly preferred embodiment the organic layer, especially theelectron transport layer comprises a mixture of a compound of formula

and a compound A-1.

The organic electronic device according to the present invention ispreferably an organic light emitting device (OLED), comprising an anode,a hole injection layer, a hole transport layer, a light emitting layer,a hole and exciton blocking layer, an electron transport layer, anelectron injection layer and a cathode, wherein the organic layercomprising the compounds of formula I and II constitutes the electrontransport layer. An exciton blocking layer, may be arranged between thehole transport layer and the light emitting layer.

Accordingly, the present invention is also directed to an electrontransport layer, comprising an organic metal complex of formula I and acompound of formula II.

The organic metal complex of formula I is contained in the organiclayer, especially the electron transport layer of an OLED in an amountof 99 to 1% weight, preferably 75 to 25% by weight, more preferablyabout 50% by weight, based on the amount of compound of formula I andII.

The synthesis of the compounds of formula II is described in J. Kido etal., Chem. Commun. (2008) 5821-5823, J. Kido et al., Chem. Mater. 20(2008) 5951-5953 and JP2008-127326, or can be done in analogy to themethods described therein.

The synthesis of the compounds of formula I is described, for example,in Christoph Schmitz et al. Chem. Mater. 12 (2000) 3012-3019 andWO00/32717, or can be done in analogy to the methods described therein.

C₁-C₁₈alkyl is typically linear or branched, where possible. Examplesare methyl, ethyl, n-propyl, isopropyl, n-butyl, sec.-butyl, isobutyl,tert.-butyl, n-pentyl, 2-pentyl, 3-pentyl, 2,2-dimethylpropyl,1,1,3,3-tetramethylpentyl, n-hexyl, 1-methylhexyl,1,1,3,3,5,5-hexamethylhexyl, n-heptyl, isoheptyl,1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl,1,1,3,3-tetramethylbutyl and 2-ethylhexyl, n-nonyl, decyl, undecyl,dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, oroctadecyl. C₁-C₈alkyl is typically methyl, ethyl, n-propyl, isopropyl,n-butyl, sec.-butyl, isobutyl, tert.-butyl, n-pentyl, 2-pentyl,3-pentyl, 2,2-dimethyl-propyl, n-hexyl, n-heptyl, n-octyl,1,1,3,3-tetramethylbutyl and 2-ethylhexyl. C₁-C₄alkyl is typicallymethyl, ethyl, n-propyl, isopropyl, n-butyl, sec.-butyl, isobutyl,tert.-butyl.

C₁-C₁₈alkoxy groups are straight-chain or branched alkoxy groups, e.g.methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy,tert-butoxy, amyloxy, isoamyloxy or tertamyloxy, heptyloxy, octyloxy,isooctyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tetradecyloxy,pentadecyloxy, hexadecyloxy, heptadecyloxy and octadecyloxy. Examples ofC₁-C₈alkoxy are methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy,sec.-butoxy, isobutoxy, tert.-butoxy, n-pentyloxy, 2-pentyloxy,3-pentyloxy, 2,2-dimethylpropoxy, n-hexyloxy, nheptyloxy, n-octyloxy,1,1,3,3-tetramethylbutoxy and 2-ethylhexyloxy, preferably C₁-C₄alkoxysuch as typically methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy,sec.-butoxy, isobutoxy, tert.-butoxy.

C₁-C₁₈perfluoroalkyl, especially C₁-C₄perfluoroalkyl, is a branched orunbranched radical such as for example —CF₃, —CF₂CF₃, —CF₂CF₂CF₃,—CF(CF₃)₂, —(CF₂)₃CF₃, and —C(CF₃)₃.

C₆-C₂₄aryl (C₆-C₁₈aryl), which optionally can be substituted, istypically phenyl, 4-methylphenyl, 4-methoxyphenyl, naphthyl, especially1-naphthyl, or 2-naphthyl, biphenylyl, terphenylyl, pyrenyl, 2- or9-fluorenyl, phenanthryl, or anthryl, which may be unsubstituted orsubstituted.

C₂-C₂₀heteroaryl represents a ring with five to seven ring atoms or acondensed ring system, wherein nitrogen, oxygen or sulfur are thepossible hetero atoms, and is typically a heterocyclic group with fiveto 30 atoms having at least six conjugated π-electrons such as thienyl,benzothiophenyl, dibenzothiophenyl, thianthrenyl, furyl, furfuryl,2H-pyranyl, benzofuranyl, isobenzofuranyl, dibenzofuranyl,phenoxythienyl, pyrrolyl, imidazolyl, pyrazolyl, pyridyl, bipyridyl,triazinyl, pyrimidinyl, pyrazinyl, pyridazinyl, indolizinyl, isoindolyl,indolyl, indazolyl, purinyl, quinolizinyl, chinolyl, isochinolyl,phthalazinyl, naphthyridinyl, chinoxalinyl, chinazolinyl, cinnolinyl,pteridinyl, carbazolyl, carbolinyl, benzotriazolyl, benzoxazolyl,phenanthridinyl, acridinyl, pyrimidinyl, phenanthrolinyl, phenazinyl,isothiazolyl, phenothiazinyl, isoxazolyl, furazanyl or phenoxazinyl,which can be unsubstituted or substituted.

The C₆-C₂₄aryl (C₆-C₁₈aryl) and C₂-C₂₀heteroaryl groups are preferablysubstituted by one, or more C₁-C₈alkyl groups.

Examples of arylene radicals are phenylene, naphthylene, phenalenylene,antracylene and phenantrylene, which may optionally be substituted byone or more C₁-C₁₈alkyl groups. A preferred arylene radical is1,3-phenylene, which may optionally be substituted by one or moreC₁-C₁₈alkyl groups.

Examples of heteroarylene radicals are 1,3,4-thiadiazol-2,5-ylene,1,3-thiazol-2,4-ylene, 1,3-thiazol-2,5-ylene, 2,4-thiophenylene,2,5-thiophenylene, 1,3-oxazol-2,4-ylene, 1,3-oxazol-2,5-ylene and1,3,4-oxadiazol-2,5-ylene, 2,5-indenylene, 2,6-indenylene, especiallypyrazinylene, pyridinylene, pyrimidinylene, and triazolylene, which mayoptionally be substituted by one or more C₁-C₁₈alkyl groups. Preferredheteroarylene radicals are 2,6-pyrazinylene, 3,5-pyridinylene,2,6-pyridinylene, 4,6-pyrimidinylene, and 2,6-triazolylene, which mayoptionally be substituted by one or more C₁-C₁₈alkyl groups.

D is preferably —CO—, —COO—, —S—, —SO—, —SO₂—, —O—, —NR²⁵—, wherein R²⁵is C₁-C₁₂alkyl, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl,isobutyl, or sec-butyl, or C₆-C₁₈aryl, such as phenyl, tolyl, naphthyl,or biphenylyl.

E is preferably —OR²⁹; —SR²⁹; —NR²⁵R²⁵; —COR²⁸; —COOR²⁷; —CONR²⁵R²⁵; or—CN; wherein R²⁵, R²⁷, R²⁸ and R²⁹ are independently of each otherC₁-C₁₂alkyl, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl,isobutyl, sec-butyl, hexyl, octyl, or 2-ethyl-hexyl, or C₆-C₁₈aryl, suchas phenyl, tolyl, naphthyl, or biphenylyl, which may optionally besubstituted.

G has the same preferences as E, or is C₁-C₁₈alkyl, especiallyC₁-C₁₂alkyl, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl,isobutyl, sec-butyl, hexyl, octyl, or 2-ethyl-hexyl, or isC₁-C₁₈perfluoroalkyl, such, for example, —CF₃.

The organic electronic device of the present application is, forexample, an organic solar cell (organic photovoltaics), a switchingelement. such as an organic transistors, for example organic FET andorganic TFT, organic light emitting field effect transistor (OLEFET), oran organic light-emitting diode (OLED), preference being given to OLEDs.

The present application relates to the use of the organic metal complexof formula I in combination with the compound of formula II as organiclayer, especially electron transport layer in an organic electronicdevice.

Accordingly, the present application is directed to an organic layer,especially electron transport layer, comprising an organic metal complexof formula I and a compound of formula II.

Suitable structures of organic electronic devices are known to thoseskilled in the art and are specified below.

The organic transistor generally includes a semiconductor layer formedfrom an organic layer with hole transport capacity and/or electrontransport capacity; a gate electrode formed from a conductive layer; andan insulating layer introduced between the semiconductor layer and theconductive layer. A source electrode and a drain electrode are mountedon this arrangement in order thus to produce the transistor element. Inaddition, further layers known to those skilled in the art may bepresent in the organic transistor.

The organic solar cell (photoelectric conversion element) generallycomprises an organic layer present between two plate-type electrodesarranged in parallel. The organic layer may be configured on a comb-typeelectrode. There is no particular restriction regarding the site of theorganic layer and there is no particular restriction regarding thematerial of the electrodes. When, however, plate-type electrodesarranged in parallel are used, at least one electrode is preferablyformed from a transparent electrode, for example an ITO electrode or afluorine-doped tin oxide electrode. The organic layer is formed from twosublayers, i.e. a layer with p-type semiconductor properties or holetransport capacity, and a layer formed with n-type semiconductorproperties or electron transport capacity. In addition, it is possiblefor further layers known to those skilled in the art to be present inthe organic solar cell. The layer with electron transport capacity maycomprise the organic metal complex of formula I and the compound offormula II.

The present invention further relates to an organic light-emitting diodecomprising an anode An and a cathode Ka, a light-emitting layer Earranged between the anode An and the cathode Ka, an electron transportlayer arranged between the cathode Ka and the light-emitting layer E,and if appropriate at least one further layer selected from the groupconsisting of at least one blocking layer for holes/excitons, at leastone blocking layer for electrons/excitons, at least one hole injectionlayer, at least one hole transport layer and at least one electroninjection layer, wherein the electron transport layer comprises anorganic metal complex of formula I and a compound of formula II.

Structure of the Inventive OLED

The inventive organic light-emitting diode (OLED) thus generally has thefollowing structure:

an anode (An) and a cathode (Ka) and a light-emitting layer E arrangedbetween the anode (An) and the cathode (Ka) and an electron transportlayer arranged between the cathode Ka and the light-emitting layer E.

The inventive OLED may, for example—in a preferred embodiment—be formedfrom the following layers:

1. Anode

2. Hole transport layer3. Light-emitting layer4. Blocking layer for holes/excitons5. Electron transport layer

6. Cathode

Layer sequences different than the aforementioned structure are alsopossible, and are known to those skilled in the art. For example, it ispossible that the OLED does not have all of the layers mentioned; forexample, OLEDs which have layers (1), (3), (4), (5) and (6), arelikewise suitable. In addition, the OLEDs may have a blocking layer forelectrons/excitons between the hole transport layer (2) and thelight-emitting layer (3).

It is additionally possible that a plurality of the aforementionedfunctions (electron/exciton blocker, hole/exciton blocker, holeinjection, hole transport, electron injection, electron transport) arecombined in one layer and are assumed, for example, by a single materialpresent in this layer. For example, a material used in the holetransport layer, in one embodiment, may simultaneously block excitonsand/or electrons.

Furthermore, the individual layers of the OLED among those specifiedabove may in turn be formed from two or more layers. For example, thehole transport layer may be formed from a layer into which holes areinjected from the electrode, and a layer which transports the holes awayfrom the hole-injecting layer into the light-emitting layer. Theelectron trans-port layer may likewise consist of a plurality of layers,for example a layer in which electrons are injected by the electrode,and a layer which receives electrons from the electron injection layerand transports them into the light-emitting layer. These layersmentioned are each selected according to factors such as energy level,thermal resistance and charge carrier mobility, and also energydifference of the layers specified with the organic layers or the metalelectrodes. The person skilled in the art is capable of selecting thestructure of the OLEDs such that it is matched optimally to the organiccompounds used as emitter substances in accordance with the invention.

In order to obtain particularly efficient OLEDs, for example, the HOMO(highest occupied molecular orbital) of the hole transport layer shouldbe matched to the work function of the anode, and the LUMO (lowestunoccupied molecular orbital) of the electron transport layer should bematched to the work function of the cathode, provided that theaforementioned layers are present in the inventive OLEDs.

The anode (1) is an electrode which provides positive charge carriers.It may be formed, for example, from materials which comprise a metal, amixture of various metals, a metal alloy, a metal oxide or a mixture ofvarious metal oxides. Alternatively, the anode may be a conductivepolymer. Suitable metals comprise metals and alloys of the metals of themain groups, transition metals and of the lanthanoids, especially themetals of groups Ib, IVa, Va and Vla of the periodic table of theelements, and the transition metals of group VIIIa. When the anode is tobe transparent, generally mixed metal oxides of groups Ilb, IIIb and IVbof the periodic table of the elements (IUPAC version) are used, forexample indium tin oxide (ITO). It is likewise possible that the anode(1) comprises an organic material, for example polyaniline, asdescribed, for example, in Nature, Vol. 357, pages 477 to 479 (Jun. 11,1992). At least either the anode or the cathode should be at leastpartly transparent in order to be able to emit the light formed. Thematerial used for the anode (1) is preferably ITO.

Suitable hole transport materials for layer (2) of the inventive OLEDsare disclosed, for example, in Kirk-Othmer Encyclopedia of ChemicalTechnology, 4th edition, Vol. 18, pages 837 to 860, 1996. Bothhole-transport molecules and polymers can be used as the hole transportmaterial. Hole-transport molecules typically used are selected from thegroup consisting of tris[N-(1-naphthyl)-N-(phenylamino)]triphenylamine(1-NaphDATA), 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (α-NPD),N,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1′-biphenyl]-4,4′-diamine(TPD), 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC),N,N′-bis(4-methylphenyl)-N,N′-bis(4-ethylphenyl)-[1,1′-(3,3′-dimethyl)biphenyl]-4,4′-diamine(ETPD), tetrakis(3-methylphenyl)-N,N,N′,N′-2,5-phenylenediamine (PDA),α-phenyl-4-N,N-diphenylaminostyrene (TPS), p-(diethylamino)benzaldehydediphenylhydrazone (DEH), triphenylamine (TPA),bis[4-(N,N-diethylamino)-2-methylphenyl)(4-methylphenyl)methane (MPMP),1-phenyl-3-[p-(diethylamino)styryl]-5-[p-(diethylamino)phenyl]pyrazoline(PPR or DEASP), 1,2-trans-bis(9H-carbazol-9-yl)cyclobutane (DCZB),N,N,N′,N′-tetrakis(4-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine (TTB),4,4′,4″-tris(N,N-diphenylamino)triphenylamine (TDTA),4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA),N,N′-bis(naphthalen-2-yl)-N,N′-bis(phenyl)benzidine (8-NPB),N,N′-bis(3-methylphenyl)N,N′-bis(phenyl)-9,9-spirobifluorene(Spiro-TPD),N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-9,9-spirobifluorene(Spiro-NPB),N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-9,9-dimethylfluorene(DMFL-TPD), di[4-(N,N-ditolylamino)phenyl]cyclohexane,N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-9,9-dimethylfluorene,N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-2,2-dimethylbenzidine,N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)benzidine,N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)benzidine,2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ),4,4′,4″-tris(N-3-methylphenyl-Nphenylamino)triphenylamine,4,4′,4″-tris(N-(2-naphthyl)-N-phenyl-amino)triphenylamine,pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile (PPDN),N,N,N′,N′-tetrakis(4-methoxyphenyl)benzidine (MeO-TPD),2,7-bis[N,N-bis(4-methoxyphenyl)amino]-9,9-spirobifluorene(MeO-Spiro-TPD),2,2′-bis[N,N-bis(4-methoxyphenyl)amino]-9,9-spirobifluorene(2,2′-MeO-Spiro-TPD),N,N′-diphenyl-N,N′-di[4-(N,N-ditolylamino)phenyl]benzidine (NTNPB),N,N′-diphenyl-N,N′-di[4-(N,N-diphenylamino)phenyl]benzidine (NPNPB),N,N′-di(naphthalen-2-yl)-N,N′-diphenylbenzene-1,4-diamine (β-NPP),N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-9,9-diphenylfluorene(DPFL-TPD),N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-9,9-diphenylfluorene(DPFL-NPB), 2,2′,7,7′-tetrakis(N,N-diphenylamino)-9,9′-spirobifluorene(Spiro-TAD), 9,9-bis[4-(N,N-bis(biphenyl-4-yl)amino)phenyl]-9H-fluorene(BPAPF), 9,9-bis[4-(N,N-bis(naphthalen-2-yl)amino)phenyl]-9H-fluorene(NPAPF),9,9-bis[4-(N,N-bis(naphthalen-2-yl)-N,N′-bisphenylamino)phenyl]-9H-fluorene(NPBAPF),2,2′,7,7′-tetrakis[Nnaphthalenyl(phenyl)amino]-9,9′-spirobifluorene(Spiro-2NPB), N,N′-bis(phenanthren-9-yl)N,N′-bis(phenyl)benzidine(PAPB),2,7-bis[N,N-bis(9,9-spirobifluoren-2-yl)amino]-9,9-spirobifluorene(Spiro-5), 2,2′-bis[N,N-bis(biphenyl-4-yl)amino]-9,9-spirobifluorene(2,2′-Spiro-DBP), 2,2′-bis(N,N-diphenylamino)-9,9-spirobifluorene(Spiro-BPA), 2,2′,7,7′-tetra(N,N-ditolyl)aminospirobifluorene(Spiro-TTB), N,N,N′,N′-tetranaphthalen-2-ylbenzidine (TNB), porphyrincompounds and phthalocyanines such as copper phthalocyanines andtitanium oxide phthalocyanines. Hole-transporting polymers typicallyused are selected from the group consisting of polyvinylcarbazoles,(phenylmethyl)polysilanes and polyanilines. It is likewise possible toobtain hole-transporting polymers by doping hole-transporting moleculesinto polymers such as polystyrene and polycarbonate. Suitablehole-transporting molecules are the molecules already mentioned above.

In addition—in one embodiment—it is possible to use carbene complexes ashole transport materials, the band gap of the at least one holetransport material generally being greater than the band gap of theemitter material used. In the context of the present application, “bandgap” is understood to mean the triplet energy. Suitable carbenecomplexes are, for example, carbene complexes as described in WO2005/019373 A2, WO 2006/056418 A2, WO 2005/113704, WO 2007/115970, WO2007/115981 and WO 2008/000727. One example of a suitable carbenecomplex is fac-Indium-tris(1,3-diphenylbenzimidazolin-2-yliden-C,C²″)(Ir(dpbic)₃) with the formula:

which is disclosed, for example, in WO2005/019373. Preferably, the holetransport layer comprises a compound of formula

doped with molybdenum oxide (MoO_(x)), especially MoO₃, or rhenium oxide(ReO_(x)), especially ReO₃. The dopant is contained in an amount of from0.1% by weight, preferably 1 to 8% by weight, more preferably 3 to 5% byweight, based on the amount of dopant and carbene complex.

The light-emitting layer (3) comprises at least one emitter material. Inprinciple, it may be a fluoroescence or phosphorescence emitter,suitable emitter materials being known to those skilled in the art. Theat least one emitter material is preferably a phosphorescence emitter.The phosphorescence emitter compounds used with preference are based onmetal complexes, and especially the complexes of the metals Ru, Rh, Ir,Pd and Pt, in particular the complexes of Ir, have gained significance.

Suitable metal complexes for use in the inventive OLEDs are described,for example, in documents WO 02/60910 A1, US 2001/0015432 A1, US2001/0019782 A1, US 2002/0055014 A1, US 2002/0024293 A1, US 2002/0048689A1, EP 1 191 612 A2, EP 1 191 613 A2, EP 1 211 257 A2, US 2002/0094453A1, WO 02/02714 A2, WO 00/70655 A2, WO 01/41512 A1, WO 02/15645 A1, WO2005/019373 A2, WO 2005/113704 A2, WO 2006/115301A1, WO 2006/067074 A1,WO 2006/056418, WO 2006121811A1, WO 2007095118 A2, WO 2007/115970, WO2007/115981 and WO 2008/000727, WO2010129323, WO2010056669 andWO10086089.

The light emitting layer comprises preferably a compound of the formula

which are described in WO 2005/019373 A2, wherein the symbols have thefollowing meanings:M¹ is a metal atom selected from the group consisting of Co, Rh, Ir, Nb,Pd, Pt, Fe, Ru, Os, Cr, Mo, W, Mn, Tc, Re, Cu, Ag and Au in anyoxidation state possible for the respective metal atom;Carbene is a carbene ligand which may be uncharged or monoanionic andmonodentate, bidentate or tridentate, with the carbene ligand also beingable to be a biscarbene or triscarbene ligand;L is a monoanionic or dianionic ligand, which may be monodentate orbidentate;K is an uncharged monodentate or bidentate ligand selected from thegroup consisting of phosphines; phosphonates and derivatives thereof,arsenates and derivatives thereof; phosphites; CO; pyridines; nitrilesand conjugated dienes which form a π complex with M¹;N1 is the number of carbene ligands, where n1 is at least 1 and whenn1>1 the carbene ligands in the complex of the formula I can beidentical or different;m is the number of ligands L, where m can be 0 or ≧1 and when m>1 theligands L can be identical or different;o is the number of ligands K, where o can be 0 or ≧1 and when o>1 theligands K can be identical or different;where the sum n1+m+o is dependent on the oxidation state andcoordination number of the metal atom and on the denticity of theligands carbene, L and K and also on the charge on the ligands, carbeneand L, with the proviso that n1 is at least 1.

The compound of formula IX is preferably a compound of the formula:

The homoleptic metal-carbene complexes may be present in the form offacial or meridional isomers, preference being given to the facialisomers.

In the case of the heteroleptic metal-carbene complexes, four differentisomers may be present, preference being given to the pseudo-facialisomers.

The compound of the formula IX is more preferably a compound of theformula

Further suitable metal complexes are the commercially available metalcomplexes tris(2-phenylpyridine)iridium(III), iridium(III)tris(2-(4-tolyl)pyridinato-N,C²′),bis(2-phenylpyridine)(acetylacetonato)iridium(III), iridium(III)tris(1-phenylisoquinoline), iridium(III)bis(2,2′-benzothienyl)pyridinato-N,C³′)(acetylacetonate),tris(2-phenylquinoline)iridium(III), iridium(III)bis(2-(4,6-difluorophenyl)pyridinato-N,C²)picolinate, iridium(III)bis(1-phenylisoquinoline)(acetylacetonate),bis(2-phenylquinoline)(acetylacetonato)iridium(III), iridium(III)bis(di-benzo[f,h]quinoxaline)(acetylacetonate), iridium(III)bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate) andtris(3-methyl-1-phenyl-4-trimethylacetyl-5-pyrazolino)terbium(III),bis[1-(9,9-dimethyl-9H-fluoren-2-yl)isoquinoline](acetylacetonato)iridium(III),bis(2-phenylbenzothiazolato)(acetylacetonato)iridium(III),bis(2-(9,9-dihexylfluorenyl)-1-pyridine)(acetylacetonato)iridium(III),bis(2-benzo[b]thiophen-2-ylpyridine)(acetylacetonato)iridium(III).

In addition, the following commercially available materials aresuitable: tris(dibenzoylacetonato)mono(phenanthroline)europium(III),tris(dibenzoylmethane)mono(phenanthroline)europium(III),tris(dibenzoylmethane)mono(5-aminophenanthroline)-europium(III),tris(di-2-naphthoylmethane)mono(phenanthroline)europium(III),tris(4-bromobenzoylmethane)mono(phenanthroline)europium(III),tris(di(biphenyl)methane)mono(phenanthroline)europium(III),tris(dibenzoylmethane)mono(4,7-diphenylphenanthroline)europium(III),tris(dibenzoylmethane)mono(4,7-di-methylphenanthroline)europium(III),tris(dibenzoylmethane)mono(4,7-dimethylphenanthrolinedisulfonicacid)europium(III) disodium salt,tris[di(4-(2-(2-ethoxyethoxy)ethoxy)benzoylmethane)]mono(phenanthroline)europium(III)andtris[d][4-(2-(2-ethoxyethoxy)ethoxy)benzoylmethane)]mono(5-aminophenanthroline)europium(III),osmium(II)bis(3-(trifluoromethyl)-5-(4-tert-butylpyridyl)-1,2,4-triazolato)diphenylmethylphosphine,osmium(II)bis(3-(trifluoromethyl)-5-(2-pyridyl)-1,2,4-triazole)dimethylphenylphosphine,osmium(II)bis(3-(trifluoromethyl)-5-(4-tert-butylpyridyl)-1,2,4-triazolato)dimethylphenylphosphine,osmium(II)bis(3-(trifluoromethyl)-5-(2-pyridyl)pyrazolato)dimethylphenylphosphine,tris[4,4′-di-tert-butyl(2,Z)-bipyridine]ruthenium(III), osmium(II)bis(2-(9,9-dibutylfluorenyl)-1-isoquinoline(acetylacetonate).

Suitable triplet emitters are, for example, carbene complexes. In oneembodiment of the present invention, the compounds of the formula X areused in the light-emitting layer as matrix material together withcarbene complexes as triplet emitters.

wherein

X is NR, S, O or PR;

R is aryl, heteroaryl, alkyl, cycloalkyl, or heterocycloalkyl;A¹ is —NR⁶R⁷, —P(O)R⁸R⁶, —PR¹⁰R¹¹, —S(O)₂R¹², —S(O)R¹³, —SR¹⁴, or —OR¹⁶;R²¹, R²² and R²³ are independently of each other aryl, heteroaryl,alkyl, cycloalkyl, or heterocycloalkyl, wherein at least on of thegroups R¹, R², or R³ is aryl, or heteroaryl;R⁴ and R⁶ are independently of each other alkyl, cycloalkyl,heterocycloalkyl, aryl, heteroaryl, a group A¹, or a group having donor,or acceptor characteristics;n2 and m1 are independently of each other 0, 1, 2, or 3;R⁶, R⁷ form together with the nitrogen atom a cyclic residue having 3 to10 ring atoms, which can be unsubstituted, or which can be substitutedwith one, or more substituents selected from alkyl, cycloalkyl,heterocycloalkyl, aryl, heteroaryl and a group having donor, or acceptorcharacteristics; and/or which can be annulated with one, or more furthercyclic residues having 3 to 10 ring atoms, wherein the annulatedresidues can be unsubstituted, or can be substituted with one, or moresubstituents selected from alkyl, cycloalkyl, heterocycloalkyl, aryl,heteroaryl and a group having donor, or acceptor characteristics; andR⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴ and R¹⁵ are independently of each otheraryl, heteroaryl, alkyl, cycloalkyl, or heterocycloalkyl. Compounds offormula X, such as, for example,

are described in WO2010079051 (PCT/EP2009/067120; in particular pages on19 to 26 and in tables on pages 27 to 34, pages 35 to 37 and pages 42 to43).

Additional matrix materials on basis of dibenzofurane are, for example,described in US2009066226, EP1885818B1, EP1970976, EP1998388 andEP2034538. Examples of particularly preferred matrix materials are shownbelow:

In the above-mentioned compounds T is O, or S, preferably O. If T occursmore than one time in a molecule, all groups T have the same meaning.

Suitable carbene complexes are known to those skilled in the art and aredescribed, for example, in WO 2005/019373 A2, WO 2006/056418 A2, WO2005/113704, WO 2007/115970, WO 2007/115981 and WO 2008/000727.

The light-emitting layer may comprise further components in addition tothe emitter material. For example, a fluorescent dye may be present inthe light-emitting layer in order to alter the emission color of theemitter material. In addition—in a preferred embodiment—a matrixmaterial can be used. This matrix material may be a polymer, for examplepoly(Nvinylcarbazole) or polysilane. The matrix material may, however,be a small molecule, for example 4, 4′-N,N′-dicarbazolebiphenyl(CDP═CBP) or tertiary aromatic amines, for example TCTA. In a preferredembodiment of the present invention, at least one of the above-mentionedmatrix materials on basis of dibenzofurane, especially at least one ofthe compounds of the formula X is used as matrix material.

In a preferred embodiment, the light-emitting layer is formed from 2 to20% by weight, preferably 5 to 17% by weight, of at least one of theaforementioned emitter materials and 80 to 98% by weight, preferably 83to 95% by weight, of at least one of the aforementioned matrixmaterials—in one embodiment at least one compound of the formula X—wherethe sum total of the emitter material and of the matrix material adds upto 100% by weight.

In a preferred embodiment, the light-emitting layer comprises a compoundof formula X, such as, for example,

or

and two carbene complexes, preferably of formula

In said embodiment, the light-emitting layer is formed from 2 to 40% byweight, preferably 5 to 35% by weight, of

and 60 to 98% by weight, preferably 65 to 95% by weight, of a compoundof the formula X and

where the sum total of the carben complexes and of the compound offormula X adds up to 100% by weight.

In a further embodiment, the above-mentioned matrix materials on basisof dibenzofurane, especially the compounds of the formula X are used ashole/exciton blocker material, preferably together with carbenecomplexes as triplet emitters. The above-mentioned matrix materials onbasis of dibenzofurane, especially compounds of the formula X may beused as matrix materials or both as matrix materials and as hole/excitonblocker materials together with carbene complexes as triplet emitters.

Suitable metal complexes for use together with the above-mentionedmatrix materials on basis of dibenzofurane, especially the compounds ofthe formula X as matrix material and/or hole/exciton blocker material,in OLEDs are thus, for example, also carbene complexes as described inWO 2005/019373 A2, WO 2006/056418 A2, WO 2005/113704, WO 2007/115970, WO2007/115981 and WO 2008/000727. Explicit reference is made here to thedisclosure of the WO applications cited, and these disclosures shall beconsidered to be incorporated into the content of the presentapplication.

Hole blocker materials typically used in OLEDs are the above-mentionedmatrix materials on basis of dibenzofurane, especially compounds offormula X, 2,6-bis(Ncarbazolyl)pyridine (mCPy),2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (bathocuproin, (BCP)),bis(2-methyl-8-quinolinato)-4-phenylphenylato)aluminum(III) (BAIq),phenothiazine S,S-dioxide derivates and1,3,5-tris(N-phenyl-2-benzylimidazolyl)benzene) (TPBI), TPBI also beingsuitable as electron-conducting material. Further suitable hole blockersand/or electron transport materials are2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1-Hbenzimidazole),2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole,8-hydroxyquinolinolatolithium,4-(naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole,1,3-bis[2-(2,2′-bipyridin-6-yl)-1,3,4-oxadiazo-5-yl]benzene,4,7-diphenyl-1,10-phenanthroline,3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole,6,6′-bis[5-(biphenyl-4-yl)-1,3,4-oxadiazo-2-yl]-2,2′-bipyridyl,2-phenyl-9,10-di(naphthalene-2-yl)anthracene,2,7-bis[2-(2,2′-bipyridin-6-yl)-1,3,4-oxadiazo-5-yl]-9,9-dimethylfluorene,1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene,2-(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline,tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane,2,9-bis(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline,1-methyl-2-(4-(naphthalene-2-yl)phenyl)-1H-imidazo[4,5-f][1,10]-phenanthroline.In a further embodiment, it is possible to use compounds which comprisearomatic or heteroaromatic rings joined via groups comprising carbonylgroups, as disclosed in WO2006/100298, disilyl compounds selected fromthe group consisting of disilylcarbazoles, disilylbenzofurans,disilylbenzothiophenes, disilylbenzophospholes, disilylbenzothiopheneS-oxides and disilylbenzothiophene S,S-dioxides, as specified, forexample, in WO2009003919 (PCT/EP2008/058207) and WO2009003898(PCT/EP2008/058106) and disilyl compounds as disclosed in WO2008/034758,as a blocking layer for holes/excitons (4) or as matrix materials in thelight-emitting layer (3).

In a preferred embodiment, the present invention relates to an inventiveOLED comprising the layers (1) anode, (2) hole transport layer, (3)light-emitting layer, (4) blocking layer for holes/excitons, (5)electron transport layer and (6) cathode, and if appropriate furtherlayers, wherein the electron transport layer comprises the organic metalcomplex of formula I and the compound of formula II.

The electron transport layer (5) of the inventive OLEDs comprises theorganic metal complex of formula I and the compound of formula II. Thelayer (5) preferably improves the mobility of the electrons.

Among the materials mentioned above as hole transport materials andelectron transport materials, some may fulfil several functions. Forexample, some of the electron-transporting materials are simultaneouslyhole-blocking materials when they have a low-lying HOMO. These can beused, for example, in the blocking layer for holes/excitons (4).

The charge transport layers can also be electronically doped in order toimprove the trans-port properties of the materials used, in orderfirstly to make the layer thicknesses more generous (avoidance ofpinholes/short circuits) and in order secondly to minimize the operatingvoltage of the device. For example, the hole transport materials can bedoped with electron acceptors; for example, phthalocyanines orarylamines such as TPD or TDTA can be doped withtetrafluorotetracyanquinodimethane (F4-TCNQ) or with molybdenum oxide(MoO_(x)), especially MoO₃, or with rhenium oxide (ReO_(x)), especiallyReO₃, or WO₃. Electronic doping is known to those skilled in the art andis disclosed, for example, in W. Gao, A. Kahn, J. Appl. Phys., Vol. 94,No. 1, 1 Jul. 2003 (p-doped organic layers); A. G. Werner, F. Li, K.Harada, M. Pfeiffer, T. Fritz, K. Leo. Appl. Phys. Lett., Vol. 82, No.25, 23 Jun. 2003 and Pfeiffer et al., Organic Electronics 2003, 4,89-103. For example, the hole transport layer may, in addition to acarbene complex, e.g. Ir(dpbic)₃, be doped with molybdenum oxide(MoO_(x)), especially MoO₃, or with rhenium oxide (ReO_(x)), especiallyReO₃, or WO₃.

The cathode (6) is an electrode which serves to introduce electrons ornegative charge carriers. Suitable materials for the cathode areselected from the group consisting of alkali metals of group la, forexample Li, Cs, alkaline earth metals of group Ila, for example calcium,barium or magnesium, metals of group Ilb of the periodic table of theelements (old IUPAC version), comprising the lanthanides and actinides,for example samarium. In addition, it is also possible to use metalssuch as aluminum or indium, and combinations of all metals mentioned. Inaddition, lithium-comprising organometallic compounds or potassiumfluoride (KF) can be applied between the organic layer and the cathodein order to reduce the operating voltage.

The OLED according to the present invention may additionally comprisefurther layers which are known to those skilled in the art. For example,a layer which facilitates the trans-port of the positive charge and/ormatches the band gaps of the layers to one another may be appliedbetween the layer (2) and the light-emitting layer (3). Alternatively,this further layer may serve as a protective layer. In an analogousmanner, additional layers may be present between the light-emittinglayer (3) and the layer (4) in order to facilitate the trans-port ofnegative charge and/or to match the band gaps between the layers to oneanother. Alternatively, this layer may serve as a protective layer.

In a preferred embodiment, the inventive OLED, in addition to layers (1)to (6), comprises at least one of the following layers mentioned below:

-   -   a hole injection layer between the anode (1) and the        hole-transport layer (2);    -   a blocking layer for electrons between the hole-transport        layer (2) and the light-emitting layer (3);    -   an electron injection layer between the electron-transport        layer (5) and the cathode (6).

Materials for a hole injection layer may be selected from copperphthalocyanine,4,4′,4″-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA),4,4′,4″-tris(N-(2-naphthyl)-N-phenylamino)triphenylamine (2T-NATA),4,4′,4″-tris(N-(1-naphthyl)-N-phenylamino)triphenylamine (1T-NATA),4,4′,4″-tris(N,N-diphenylamino)triphenylamine (NATA), titanium oxidephthalocyanine, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane(F4-TCNQ), pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile(PPDN), N,N,N′,N′-tetrakis(4-methoxyphenyl)benzidine (MeO-TPD),2,7-bis[N,N-bis(4-methoxyphenyl)amino]-9,9-spirobifluorene(MeO-Spiro-TPD),2,Z-bis[N,N-bis(4-methoxyphenyl)amino]-9,9-spirobifluorene(2,Z-MeO-Spiro-TPD),N,N′-diphenyl-N,N′-di-[4-(N,N-ditolylamino)phenyl]benzidine (NTNPB),N,N′-diphenyl-N,N′-di-[4-(N,N-diphenylamino)phenyl]benzidine (NPNPB),N,N′-di(naphthalen-2-yl)-N,N′-diphenylbenzene-1,4-diamine (α-NPP). Inprinciple, it is possible that the hole injection layer comprises atleast one of the above-mentioned matrix materials on basis ofdibenzofurane, especially at least one compound of the formula X as holeinjection material.

As a material for the electron injection layer, KF, or Liq, for example,can be selected. KF is more preferred than Liq.

The person skilled in the art is aware (for example on the basis ofelectrochemical studies) of how suitable materials have to be selected.Suitable materials for the individual layers are known to those skilledin the art and are disclosed, for example, in WO 00/70655.

In addition, it is possible that some of the layers used in theinventive OLED have been surface-treated in order to increase theefficiency of charge carrier transport. The selection of the materialsfor each of the layers mentioned is preferably determined by obtainingan OLED with a high efficiency and lifetime.

The inventive OLED can be produced by methods known to those skilled inthe art. In general, the inventive OLED is produced by successive vapordeposition of the individual layers onto a suitable substrate. Suitablesubstrates are, for example, glass, inorganic semitransports, typicallyITO, or IZO, or polymer films. For vapor deposition, it is possible touse customary techniques, such as thermal evaporation, chemical vapordeposition (CVD), physical vapor deposition (PVD) and others. In analternative process, the organic layers of the OLED can be applied fromsolutions or dispersions in suitable solvents, employing coatingtechniques known to those skilled in the art.

In general, the different layers have the following thicknesses: anode(1) 50 to 500 nm, preferably 100 to 200 nm; hole-conducting layer (2) 5to 100 nm, preferably 20 to 80 nm, light-emitting layer (3) 1 to 100 nm,preferably 10 to 80 nm, blocking layer for holes/excitons (4) 2 to 100nm, preferably 5 to 50 nm, electron-conducting layer (5) 5 to 100 nm,preferably 20 to 80 nm, cathode (6) 20 to 1000 nm, preferably 30 to 500nm. The relative position of the recombination zone of holes andelectrons in the inventive OLED in relation to the cathode and hence theemission spectrum of the OLED can be influenced, among other factors, bythe relative thickness of each layer. This means that the thickness ofthe electron transport layer should preferably be selected such that theposition of the recombination zone is matched to the optical resonatorproperty of the diode and hence to the emission wavelength of theemitter. The ratio of the layer thicknesses of the individual layers inthe OLED depends on the materials used. The layer thicknesses of anyadditional layers used are known to those skilled in the art. It ispossible that the electron-conducting layer and/or the hole-conductinglayer have greater thicknesses than the layer thicknesses specified whenthey are electrically doped.

Use of the electron transport layer of the present application makes itpossible to obtain OLEDs with high efficiency and with low operatingvoltage. Frequently, the OLEDs obtained by the use of the electrontransport layer of the present application additionally have highlifetimes. The efficiency of the OLEDs can additionally be improved byoptimizing the other layers of the OLEDs. Shaped substrates and novelhole-transport materials which bring about a reduction in the operatingvoltage or an increase in the quantum efficiency are likewise usable inthe inventive OLEDs. Moreover, additional layers may be present in theOLEDs in order to adjust the energy level of the different layers and tofacilitate electroluminescence.

The OLEDs may further comprise at least one second light-emitting layer.The overall emission of the OLEDs may be composed of the emission of theat least two light-emitting layers and may also comprise white light.

The OLEDs can be used in all apparatus in which electroluminescence isuseful. Suitable devices are preferably selected from stationary andmobile visual display units and illumination units. Stationary visualdisplay units are, for example, visual display units of computers,televisions, visual display units in printers, kitchen appliances andadvertising panels, illuminations and information panels. Mobile visualdisplay units are, for example, visual display units in cellphones,laptops, digital cameras, MP3 players, vehicles and destination displayson buses and trains. Further devices in which the inventive OLEDs can beused are, for example, keyboards; items of clothing; furniture;wallpaper.

In addition, the electron transport layer of the present application canbe used in OLEDs with inverse structure. The structure of inverse OLEDsand the materials typically used therein are known to those skilled inthe art.

In addition, the present invention relates to an apparatus selected fromthe group consisting of stationary visual display units such as visualdisplay units of computers, televisions, visual display units inprinters, kitchen appliances and advertising panels, illuminations,information panels, and mobile visual display units such as visualdisplay units in cellphones, laptops, digital cameras, MP3 players,vehicles and destination displays on buses and trains; illuminationunits; keyboards; items of clothing; furniture; wallpaper, comprisingthe inventive organic electronic device, or the inventive organic layer,especially electron trans-port layer.

The following examples are included for illustrative purposes only anddo not limit the scope of the claims. Unless otherwise stated, all partsand percentages are by weight.

EXAMPLES Comparative Application Example 1

The ITO substrate used as the anode is first cleaned with commercialdetergents for LCD production (Deconex® 20NS, and 250RGAN-ACID®neutralizing agent) and then in an acetone/isopropanol mixture in anultrasound bath. To eliminate any possible organic residues, thesubstrate is exposed to a continuous ozone flow in an ozone oven for afurther 25 minutes. This treatment also improves the hole injectionproperties of the ITO. Then AJ20-1000 (commercially available fromPlexcore) is spin-coated and dried to form a hole injection layer (˜40nm).

Thereafter, the organic materials specified below are applied by vapordeposition to the clean substrate at a rate of approx. 0.5-5 nm/min atabout 10⁻⁸ mbar. As a hole transport and exciton blocker, Ir(dpbic)₃(V1) is applied to the substrate with a thickness of 45 nm, wherein thefirst 35 nm are doped with MoOx (˜50%) to improve the conductivity.

Ir(dpbic)₃ (for preparation, see Ir complex (7) in the application WO2005/019373).

Subsequently, a mixture of 30% by weight of compound

35% by weight of compound (V1) and 35% by weight of compound

described in PCT/EP2009/067120) is applied by vapor deposition in athickness of 20 nm.

Subsequently, the material

is applied by vapor deposition with a thickness of 5 nm as exciton andhole blocker.

Next, a mixture of 50% by weight of

and 50% by weight of

(8-hydroxyquinolinolato-lithium (Liq)) is applied as electron transportlayer by vapor deposition in a thickness of 40 nm, as are a 2 nm-thickpotassium fluoride layer (electron injection layer) and finally a 100nm-thick Al electrode.

Comparative Application Example 2

Production and construction of an OLED as in the comparative applicationexample 1, except compound

is used alone instead of the mixture of BCP and Liq.

Comparative Application Example 3

Production and construction of an OLED as in the comparative applicationexample 1, except Liq is used alone instead of the mixture of BCP andLiq.

Application Example 1

Production and construction of an OLED as in the comparative applicationexample 1, except a mixture of 75% by weight of compound A-1 and 25% byweight of Liq is used instead of the mixture of BCP and Liq.

Application Example 2

Production and construction of an OLED as in the comparative applicationexample 1, except a mixture of 50% by weight of compound A-1 and 50% byweight of Liq is used instead of the mixture of BCP and Liq.

Application Example 3

Production and construction of an OLED as in the comparative applicationexample 1, except a mixture of 25% by weight of compound A-1 and 75% byweight of Liq is used instead of the mixture of BCP and Liq.

To characterize the OLED, electroluminescence spectra are recorded atvarious currents and voltages. In addition, the current-voltagecharacteristic is measured in combination with the light output emitted.The light output can be converted to photometric parameters bycalibration with a photometer. To determine the lifetime, the OLED isoperated at a constant current density and the decrease in the lightoutput is recorded. The lifetime is defined as that time which lapsesuntil the luminance decreases to half of the initial luminance.

V at 300 cd/m², Im/W at 300 cd/m², EQE (%) at 300 cd/m² and lifetime (h)at 300 cd/m² measured for the devices of the Application Examples andComparative Application Examples are shown in the Tables 1-1 and 1-2below, wherein the measured data of the Comparative Application Example1 (Table 1-1) and 3 (Table 1-2), respectively are set to 100 and thedata of the Application Examples are specified in relation to those ofComparative Application Example 1 and 3, respectively.

TABLE 1-1 V at Im/W at EQE⁴⁾ (%) Lifetime (h) ET 300 300 at at 300Device Layer cd/m² cd/m² 300 cd/m² cd/m² Color Appl. Liq¹⁾ 86 177 144567 X = 0.174 Ex. 2 Cpd. Y = 0.310 A-1¹⁾ Comp. Liq¹⁾ 100 100 100 100 X =0.167 Appl. BCP¹⁾ Y = 0.282 Ex. 1

TABLE 1-2 V at Im/W EQE⁴⁾ (%) Lifetime (h) ET 300 300 at at Device Layercd/m² cd/m² 300 cd/m² 300 cd/m² Color Appl. Liq²⁾ 43 297 124 206 X =0.174 Ex. 1 Cpd. A-1³⁾ Y = 0.312 Appl. Liq¹⁾ 44 271 116 272 X = 0.174Ex. 2 Cpd. A-1¹⁾ Y = 0.310 Appl. Liq³⁾ 51 230 114 392 X = 0.173 Ex. 3Cpd. A-1²⁾ Y = 0.309 Comp. Cpd. A-1 44 264 112 132 X = 0.175 Appl. Y =0.314 Ex. 2 Comp. Liq 100 100 100 100 X = 0.171 Appl. Y = 0.300 Ex. 3¹⁾50% by weight. ²⁾25% by weight ³⁾75% by weight ⁴⁾External quantumefficiency (EQE) is # a of generated photons escaped from a substance ora device/# of electrons flowing through it. ET Layer = ElectronTransport Layer. EI Layer = Electron Injection Layer.

The life time, power efficiency, quantum efficiency and/or voltage at300 cd/m² of the devices of the Application Examples are superior ascompared with the devices of the Comparative Application Examples.

1. An organic electronic device including a first electrode, a secondelectrode, and an organic layer interposed between the first electrodeand the second electrode, wherein the organic layer comprises an organicmetal complex of formula

and a compound of formula

wherein R¹ and R² are independently of each other F, C₁-C₈alkyl, orC₆-C₁₈aryl, which may optionally be substituted by one, or moreC₁-C₈alkyl groups, or two substituents R¹ and/or R² combine to form afused benzene ring group, which may optionally be substituted by one, ormore C₁-C₈alkyl groups, a and b are independently of each other 0, or aninteger 1 to 3, R⁸¹, R⁸², R⁸³, R⁸⁴, R⁸¹′, R⁸²′, R⁸³′, and R⁸⁴′ areindependently of each other H, C₁-C₁₈alkyl, C₁-C₁₈alkyl which issubstituted by E and/or interrupted by D, C₆-C₂₄aryl, C₆-C₂₄aryl whichis substituted by G, C₂-C₂₀heteroaryl, or C₂-C₂₀heteroaryl which issubstituted by G, Q is an arylene or heteroarylene group, each of whichmay optionally be substituted by G; D is —CO—; —COO—; —S—; —SO—; —SO₂—;—O—; —NR²⁵—; —SiR³⁰R³¹—; —POR³²—; —CR²³═CR²⁴—; or —C≡C—; and E is —OR²⁹;—SR²⁹; —NR²⁵R²⁶; —COR²⁸; —COOR²⁷; —CONR²⁵R²⁶; —CN; or F; G is E,C₁-C₁₈alkyl, C₁-C₁₈alkyl which is interrupted by D,C₁-C₁₈perfluoroalkyl, C₁-C₁₈alkoxy, or C₁-C₁₈alkoxy which is substitutedby E and/or interrupted by D, wherein R²³ and R²⁴ are independently ofeach other H, C₆-C₁₈aryl; C₆-C₁₈aryl which is substituted byC₁-C₁₈alkyl, or C₁-C₁₈alkoxy; C₁-C₁₈alkyl; or C₁-C₁₈alkyl which isinterrupted by —O—; R²⁵ and R²⁶ are independently of each otherC₆-C₁₈aryl; C₆-C₁₈aryl which is substituted by C₁-C₁₈alkyl, orC₁-C₁₈alkoxy; C₁-C₁₈alkyl; or C₁-C₁₈alkyl which is interrupted by —O—;or R²⁵ and R²⁶ together form a five or six membered ring, R²⁷ and R²⁸are independently of each other C₆-C₁₈aryl; C₆-C₁₈aryl which issubstituted by C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; C₁-C₁₈alkyl; or C₁-C₁₈alkylwhich is interrupted by —O—, R²⁹ is C₆-C₁₈aryl; C₆-C₁₈aryl, which issubstituted by C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; C₁-C₁₈alkyl; or C₁-C₁₈alkylwhich is interrupted by —O—, R³⁰ and R³¹ are independently of each otherC₁-C₁₈alkyl, C₆-C₁₈aryl, or C₆-C₁₈aryl, which is substituted byC₁-C₁₈alkyl, R³² is C₁-C₁₈alkyl, C₆-C₁₈aryl, or C₆-C₁₈aryl, which issubstituted by C₁-C₁₈alkyl M is an alkali metal atom, or an earthalkaline metal atom, n is 1, if M is an alkali metal atom, n is 2, if Mis an earth alkali metal atom.
 2. The organic electronic deviceaccording to claim 1, wherein Q is a group of formula

wherein R⁸⁵ is H, C₁-C₁₈alkyl, C₁-C₁₈alkyl which is substituted by Eand/or interrupted by D, C₆-C₂₄aryl, C₆-C₂₄aryl which is substituted byG, C₂-C₂₀heteroaryl, or C₂-C₂₀heteroaryl which is substituted by G, andD, E and G are as defined in claim
 1. 3. The organic electronic deviceaccording to claim 2, wherein the compound of formula II is a compoundof formula

wherein Q is

R⁸⁵ is H, or C₁-C₁₈alkyl and R⁸⁵′ is H, C₁-C₁₈alkyl, or


4. The organic electronic device according to claim 3, wherein thecompound of formula IIb is a compound of formula


5. The organic electronic device according to claim 1, wherein M is Li,Na, or K and n is
 1. 6. The organic electronic device according to claim5, wherein the compound of formula I is a compound of formula


7. The organic electronic device according to claim 1, which is anorganic light emitting device, comprising an anode, a hole injectionlayer, a hole transport layer, a light emitting layer, a hole andexciton blocking layer, an electron transport layer, an electroninjection layer and a cathode, wherein the organic layer comprising thecompounds of formula I and II constitutes the electron transport layer.8. The organic electronic device according to claim 7, wherein theelectron transport layer comprises a mixture of a compound of formula

and a compound of formula (A-1).
 9. The organic electronic deviceaccording to claim 7, wherein the electron injection layer comprises, orconsists of potassium fluoride.
 10. The organic electronic deviceaccording to any of claim 7, wherein the light emitting layer comprisesa compound of the formula

wherein the symbols have the following meanings: M¹ is a metal atomselected from the group consisting of Co, Rh, Ir, Nb, Pd, Pt, Fe, Ru,Os, Cr, Mo, W, Mn, Tc, Re, Cu, Ag and Au in any oxidation state possiblefor the respective metal atom; carbene is a carbene ligand which may beuncharged or monoanionic and monodentate, bidentate or tridentate, withthe carbene ligand also being able to be a biscarbene or triscarbeneligand; L is a monoanionic or dianionic ligand, which may be monodentateor bidentate; K is an uncharged monodentate or bidentate ligand selectedfrom the group consisting of phosphines; phosphonates and derivativesthereof, arsenates and derivatives thereof; phosphites; CO; pyridines;nitriles and conjugated dienes which form a π complex with Ml; n1 is thenumber of carbene ligands, where n1 is at least 1 and when n1>1 thecarbene ligands in the complex of the formula I can be identical ordifferent; m is the number of ligands L, where m can be 0 or 1 and whenm>1 the ligands L can be identical or different; o is the number ofligands K, where o can be 0 or 1 and when o>1 the ligands K can beidentical or different; where the sum n1+m+o is dependent on theoxidation state and coordination number of the metal atom and on thedenticity of the ligands carbene, L and K and also on the charge on theligands, carbene and L, with the proviso that n1 is at least
 1. 11. Theorganic electronic device according to claim 10, wherein the compound ofthe formula IX is a compound of the formula


12. The organic electronic device according to claim 1, wherein the holetransport layer comprises a compound of formula

doped with molybdenum oxide (MoO_(x)), especially MoO₃, or rhenium oxide(ReO_(x)), especially ReO₃.
 13. An organic electron transport layer,comprising an organic metal complex of formula I as defined in claim 1and a compound of formula II as defined in claim
 1. 14. A method ofusing the organic layer according to claim 13 in an organic electronicdevice.
 15. An apparatus comprising an organic electronic deviceaccording to claim
 1. 16. An apparatus comprising an organic electrontransport layer according to claim 13.